Method for the production of bearing materials, bearing materials produced by said methods and use of said bearing materials

ABSTRACT

A method for the production of bearing materials is disclosed, in which a strip of a metallic woven support is continuously provided with a slip layer mostly comprising polytetrafluoroethylene (PTFE), covering one side thereof. The woven support is coated on one side with a paste of the material for the slip layer, whereby the woven support runs with the lower surface thereof in full-surface contact with a roller during and directly after the coating.

The present invention relates to a method of producing bearing materialshaving the features of the precharacterizing clause of claim 1, bearingmaterials produced using this method and use of these bearing materials.

In order to produce materials for composite bearings provided with aplastics overlay, it is known to provide a plastics overlay on a solid,especially strip-form backing framework, preferably of steel, a copperand/or an aluminum alloy, wherein this plastics overlay comprises asbase material polytetrafluoroethylene (PTFE), to which further additionsare optionally added, for example further polymers or wear- and/orfriction-reducing additions. An overlay dispersion or paste is applieduniformly to this solid metallic backing framework, which in DE 11 32710 AS is also known as a porous metal strip, with the assistance of aroll pair arranged downstream, such that the solid backing frameworkcoated in this way may then be subjected to heat treatment.

It is also known to use a metallic backing fabric instead of the backingframework described above, which fabric is provided with an overlaycovering one side of the backing fabric and containing mainlypolytetrafluoroethylene. In order to produce this known backing fabric,a method is used in which a web of the metallic backing fabric isprovided continuously with a film applied to one side of the backingfabric, which film contains the overlay material. In the known method,the backing fabric covered in this way with the film is then guidedthrough an appropriate press, such that the film is pressed into thefabric structure of the backing fabric on one side.

The known method described above has the disadvantage, however, that thefilms of overlay material required therefor can only be produced with arelatively large amount of effort, such that the bearing materialsproduced by this method have a relatively high production price.

The object of the present invention is to provide a method of producingbearing materials of the type indicated, with which a metallic backingfabric may be provided particularly simply and continuously with anappropriate overlay.

This object is achieved according to the invention by a method havingthe characterizing features of claim 1.

As with the above-mentioned prior art, the method according to theinvention for producing bearing materials likewise provides for a web ofa metallic backing fabric to be provided continuously with an overlaycovering the backing fabric on one side and mainly containingpolytetrafluoroethylene (PTFE), wherein, in contrast to the above-statedprior art, the backing fabric is not coated on its top face with a filmbut instead with a paste of the overlay material. In the methodaccording to the invention, the bottom face of the backing fabric isguided during and immediately after coating in all-over contact with aroll, in such a way that, prior to coating, the overlay material pasteis applied to the top face of the backing fabric, while the opposingface of the backing fabric, also abbreviated to bottom face in thepresent application, is guided during and immediately after this coatingprocess in all-over contact with a roll, such that, in this processingstate, the bottom face of the backing fabric thus lies on the surface ofthe roll. Preferably, the underside (bottom face) of the backing fabricis also in all-over contact with the roll immediately prior to thecoating process.

The method according to the invention exhibits a number of advantages.For instance, it should first of all be noted that the method accordingto the invention, in contrast to the above-described known method inwhich a film containing the overlay material is applied to the metallicbacking fabric, allows substantially more reasonably priced productionof bearing materials, especially since the method according to theinvention is a single-stage method and dispenses completely with theseparate production of a film. Furthermore, the method according to theinvention multiplies the range of possible overlay materials, since inthe known method suitable films cannot be produced from all the possibleoverlay materials. Because with the method according to the inventionthe pasty overlay material is applied directly to the top face of themetallic backing fabric, not only may the composition of the overlay bevaried without great effort but also the thickness thereof, which islikewise not possible in the above-mentioned prior art. It hassurprisingly been noted that only the above-described one-sided all-oversupport of the bottom face of the backing fabric on the roll surfaceduring and immediately after coating and preferably also additionallyprior to coating effectively prevents pasty overlay material fromaccumulating undesirably on the bottom face of the backing fabric, aswas always the case with direct coating of the backing fabric with thepasty overlay material, i.e. without the provision of correspondingsupport on a roll surface. It is therefore only by applying the methodaccording to the invention that simple and problem-free production of abacking fabric properly provided with an overlay mainly on one sidebecomes possible.

In the context of the present description, the term backing fabriccovers all structures which are especially distinguished in thatopenings are provided between the bottom face and the top face, throughwhich the pasty material applied to the top face may penetrate throughto the bottom face during coating.

The term coating denotes all application methods with which apredetermined and adjustable amount of pasty overlay material may beapplied to the top face of the backing fabric, in particular pouring,spreading and/or spraying of the pasty material, in particular usingappropriate coating knife or nozzle systems. Furthermore, this termcoating also in particular covers application of the pasty overlaymaterial by means of at least two rolls, wherein one roll, preferably anupper roll, applies the pasty overlay material to the top face of thebacking fabric and there at the same time distributes it evenly over thetop face and into the openings, while a second roll, preferably a lowerroll, is in contact with the bottom face of the backing fabric.

A particularly suitable first embodiment of the method according to theinvention is characterized in that the web of backing fabric is guidedthrough the nip of a calender to coat the backing fabric with the pastyoverlay material, wherein the calender comprises at least one upper rolland at least one lower roll.

The upper roll of the calender may exhibit a smaller diameter than thelower roll and/or the lower roll of the calender may be roughened. Thediameter of the upper roll amounts preferably to <70% of the diameter ofthe lower roll.

This nip has the effect that, on the one hand, application of the pastyoverlay material is rendered uniform and reproducible while, on theother hand, the amount of pasty material applied and the degree ofpenetration thereof into the fabric spaces may be varied by varying thelinear pressure. The roughened surface of the lower roll lyingunderneath in all-over contact with the bottom face of the backingfabric ensures that no water is discharged at the underside of thebacking fabric, which would result in non-uniform coverage of the topface or even the occurrence of areas completely devoid of coating. Sincewith the method according to the invention this water discharge is thusprevented, the desired one-sided, uniform coverage of the fabricstructure by the pasty overlay material, i.e. the arrangement of thispasty material predominantly in and on the top face of the backingfabric, is achieved, such that the bottom face of the backing fabric,especially in the outer area thereof, accordingly does not exhibit anypasty overlay material.

The discharge of water is especially minimized when a roll is selectedas lower roll whose surface facing the backing fabric, i.e. thus thesurface which comes into contact with the bottom face of the backingfabric immediately prior to and during coating, is provided withparticles and/or unevennesses of the order of between 5 μm and 50 μm,preferably with particles and/or unevennesses of the order of between 10μm and 30 μm. This surface of the lower roll comprises theabove-mentioned particles or unevennesses in a uniform distribution. Byselecting such a lower roll, whose surface exhibits uniform definedroughness produced by the particles or unevennesses, it is possible toprevent particularly effectively and reproducibly the above-describeddischarge of liquid, especially water, during the coating process, withthe consequence that, in the case of a backing fabric treated in thisway, only the top face and at most also the spaces in the fabric is/areprovided with the overlay material and that a particularly uniform,defect-free top face is obtained.

Unevennesses are understood to mean regular or irregular surfacetexturing which may be produced by appropriate mechanical or othertreatment, for example by sandblasting or laser beam treatment. Roughsurfaces may also be distinguished in that the surface of the lower rollis preferably provided with corresponding engraving, for instanceespecially with pearlescent engraving.

A particularly preferred further development of the method according tothe invention is characterized in that the surface of the lower roll isprovided with a wrapping, in order to produce the above-describedroughness on the surface of this lower roll. In particular, a wrappingof paper, preferably of hydrophobized paper, plastics or textiles isselected therefor, wherein, through selection of the surface smoothnessof the associated wrapping, the desired roughness of the surface of thelower roll may be set. This embodiment of the method according to theinvention exhibits the additional advantage that the surface roughnessof the lower roll may be varied very quickly, since it is merelynecessary therefor to replace the associated wrapping. When usingwrappings of paper or textile, care must be taken to ensure that theassociated wrapping, which comes into contact with the bottom face ofthe backing fabric, is especially water-impermeable and/or hydrophobic,which may be achieved simply and without difficulty, for example byappropriate coatings or by selecting hydrophobic fibers.

A particularly advantageous further development of the above-describedembodiment of the method according to the invention is characterized inthat the lower roll is provided with a wrapping as mentioned aboveconsisting of a film of biaxially oriented polyester or of biaxiallyoriented polycarbonate, wherein such a film in itself exhibits thehydrophobia necessary for preventing the undesired discharge of water orother liquid via the bottom face of the backing fabric. Furthermore,these films have the additional advantage that, in addition to excellentstrength due to their biaxial orientation, these films also exhibit goodchemical resistance, such that a corresponding lower roll provided withsuch a wrapping has a long service and operating life.

In order, in the case of the method according to the invention, toproduce the above-described roughness and/or the particles on thesurface of the lower roll, a further embodiment of the method accordingto the invention is characterized in that the corresponding surface,which comes into contact with the bottom face of the backing fabricimmediately prior to and during coating, is engraved and especiallysandblasted to form the roughness and/or the particles, wherein thedesired roughness of the surface of the further web may be setparticularly simply, cheaply and without difficulty by the intensity ofthe sandblasting, the grain size selected therefor and the exposuretime.

In order, in the case of the method according to the invention, toprevent particularly effectively the discharge of pasty material, wateror another liquid at the underside of the backing fabric during coatingand thus to ensure that the top face is uniformly covered and that thebottom face of the backing fabric as far as possible does not come intocontact with the overlay material, in a particularly preferredembodiment the backing fabric is fed to the calender in such a way thatit partially loops round the lower roll, which is preferably providedwith a roughened surface. The looping distance ranges from at least 1%and preferably more than 3% of the circumference of the lower roll,wherein the above-stated looping distance depends in particular on therate of coating of the backing fabric, the thickness of application ofthe pasty overlay material and the viscosity of the pasty overlaymaterial. Looping distances which are particularly suitable amount to 5%to 25% of the circumference ofthe lower roll.

In principle, thc above-described embodiments of the method according tothe invention provide the possibility of feeding the backing fabric tothe calender during coating at any desired angle, wherein, to ensureproblem-free coating, contact between the backing fabric and the upperroll should be prevented. It is particularly advantageous for thebacking fabric to be fed virtually horizontally directly prior to andduring coating, wherein the angle of inclination is to be selected insuch a way that rolling back of the paste is prevented. Virtuallyhorizontal backing fabric feed during coating may be achieved, forexample, in that the calender, used for coating comprises the largestlower roll possible. Rolls of different diameters are preferred,wherein, as explained above, the upper roll of the calender has asmaller diameter than the lower roll of the calender, preferablyamounting to <70% of the diameter of the lower roll. By selecting such alower calender roll diameter, it is relatively simple to feed thebacking fabric to the calender in such a way that the bottom face of thebacking fabric lies on the surface of the lower roll, especially on theroughened surface of the lower roll, immediately prior to and duringcoating, and that in addition the backing fabric is guided horizontallyor virtually horizontally immediately prior to and during coating.

In an advantageous development of the method according to the invention,a third roll is associated with the calender, the axis of which roll ispreferably positioned downstream of the calender in the backing fabricconveying direction, beneath a plane extending through the nipperpendicularly to the connecting plane of the two roll axes, wherebythe backing fabric is guided in such a way that its underside is guidedin contact with the lower calender roll. The looping distance and theradius of curvature of the deflection may be optimized by thearrangement and size of the third roll. Depending on the respectivematerial of the overlay paste, paste application may be optimized bychanging the looping distance and reducing the radius of curvature.

In order to ensure the above-claimed horizontal feed of the backingfabric immediately prior to and/or during coating with simultaneouslooping round the lower roll, a further development of the methodaccording to the invention is characterized in that the connecting planethrough the axes of the two calender rolls is inclined in the backingfabric conveying direction. The angle of inclination is preferably 5° to25°. In other words, in this embodiment of the method according to theinvention, the calender used is not one with the axes of rolls arrangedvertically one above the other, but rather a calender is used in whichthe axis of the upper roll is inclined relative to the axis of the lowerroll by an angle of between 5° and 25°, preferably when viewed in thebacking fabric conveying direction.

As stated repeatedly above with regard to the methods according to theinvention, a paste of the material constituting the overlay is appliedto one side of the backing fabric in the method according to theinvention. In order to adjust the consistency of this paste to therespective backing fabric, which may exhibit different densities due todifferent backing fabric constructions, a different amount of liquid,for instance water in particulars is added to the material. However, itis particularly suitable, in the case of the method according to theinvention, for only water and not an organic solvent to be used as theliquid, wherein a wetting agent is added to the water, in order therebyto adjust the paste to the desired consistency. A non-ionic wettingagent, and preferably a wetting agent based on all alkyl polyglycolether, is in particular selected therefor, wherein, however, otherwetting agents, for example in particular alkylaryl polyglycol ethers,alkylamine polyglycol ethers, alkylamine oxides and/or fatty acid estersof polyalcohols, may also be used.

In order to vary the desired properties of the overlay produced on oneside of the backing fabric, another development of the method accordingto the invention is characterized in that the overlay material pastecontains, in addition to polytetrafluoroethylene (PTFE), at least oneother polymer, preferably at least one high temperature-resistantpolymer.

In the above-described development of the method according to theinvention, the high temperature-resistant polymer preferably comprises apolymer selected from the group comprising filly aromatic polyesters,fully aromatic polyamides, polyetherether ketones and/or polyphenylenesulfones.

If it is desired, using the method according to the invention, toproduce particularly temperature-resistant overlays with a particularlyhigh load-carrying capacity in one-sided manner on the top face of thebacking fabric, another embodiment of the method according to theinvention is characterized in that a paste is selected which contains,in addition to polytetrafluoroethylene (PTFE), between 20 vol. % and 60vol. % of the high temperature-resistant polymer, especially theabove-mentioned polymers.

In addition, the method according to the invention provides thepossibility of replacing a proportion of the polytetrafluoroethylene,preferably up to 50 vol. % of the polytetrafluoroethylene (PTFE), withother polymers and especially withpoly(tetrafluoroethylene-co-perfluorovinyl methyl ether) (PFA),poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP),poly(hexafluoroisobutylene-covinylidene fluoride) (CM-1),poly(ethylene-alt-tetrafluoroethylene) (ETFE) and/or polyvinylidenefluoride (PVDF), as proposed by a further development of the methodaccording to the invention.

A further modification of the overlay arranged in one-sided manner onthe top face of the backing fabric may be achieved in that, in a furtherdevelopment of the method according to the invention, an overlaymaterial paste is used in which up to 50 vol. % of the hightemperature-resistant polymer is replaced by molybdenum sulfide,tungsten sulfide, boron nitride, graphite, lead, lead oxide, ironoxides, calcium fluoride, glass and/or ceramic powder and/or glassand/or carbon fibers Such a modification of the pasty material appliedto the backing fabric allows the properties of the overlay to beadjusted particularly simply and effectively to the respectiverequirements, wherein it is merely necessary to produce appropriatelypasty materials.

In order to finish the bearing material produced using the methodaccording to the invention, a further development of the methodaccording to the invention is characterized in that, after coating ofthe backing fabric, the coated backing fabric is subjected, optionallyafter pre-drying, to heat treatment and rolling, in order to fix theoverlay permanently on the backing fabric and to achieve the finalthickness. A cutting process may then optionally follow, for sizing thebacking fabric provided on one side with the overlay, the backing fabricthen being coiled for further processing, wherein both coating and heattreatment and also sizing with regard to thickness and width arepreferably performed continuously.

The present invention additionally relates to a bearing materialproduced using one of the above-described embodiments of the methodaccording to the invention, wherein the bearing material according tothe invention comprises a backing fabric which is provided on its onesurface with an overlay predominantly of polytetrafluoroethylene and asfar as possible has no overlay on its other surface (bottom face).

The bearing material according to the invention is used especially as asliding element in flanged bushes and preferably for vehicle doorhinges, wherein special emphasis should be laid in particular on thefavorable price of a bearing material produced in this way, in additionto its excellent long-term load-carrying capacity while retainingproblem-free functioning.

All the concentrations stated in volume percent in this descriptionrelate to the finished overlay.

Advantageous further developments of the method according to theinvention are indicated in the subclaims.

The bearing material according to the invention is explained in moredetail below with reference to FIG. 1 and the method according to theinvention is explained in more detail below with reference to fourexemplary embodiments, illustrated schematically in FIGS. 2 to 5. In thedrawings:

FIG. 1 is a schematic sectional view through a backing fabric providedon one side with an overlay;

FIG. 2 is a schematic representation of a first embodiment of the methodaccording to the invention;

FIG. 3 is a schematic representation of a second embodiment of themethod according to the invention; and

FIG. 4 is a schematic representation of a third embodiment of the methodaccording to the invention;

FIG. 5 is a schematic representation of a fourth embodiment of themethod according to the invention.

The backing fabric illustrated schematically in FIG. 1 and designatedoverall as 1 comprises a first thread system 3 and a second threadsystem 2 extending perpendicularly thereto, wherein the thread systems 2and 3 consist of metal wires. The backing fabric 1 is provided on itstop face with an overlay 4, wherein the overlay 4, which mainly containspolytetrafluoroethylene, covers the backing fabric 1 in one-sided manneras far as its top face is concerned and thus projects thereabove. Theopposing bottom face is provided in part with the identical overlaymaterial 5, wherein, however, the overlay 5, unlike the overlay 4, doesnot cover the bottom face of the backing fabric 1, such that parts ofthe thread systems 3 a, 2 a and 3 b form the outer bottom face of thebacking fabric 1.

In FIGS. 2 to 5 the same elements are provided with the same referencenumerals.

All the embodiments illustrated schematically in FIGS. 2 to 5 of themethod for producing bearing materials provide a supply roller a for theweb of metallic backing fabric 1, wherein the roller a takes the form ofan unwinding roller for the backing fabric 1. In the conveying directionof the backing fabric 1, which is identified by the arrow A, a calender2 is in each case provided whose rolls form a nip through which thebacking fabric is guided for coating purposes, wherein in the fourembodiments illustrated the calender 2 is of differing constructions, aswill be described more fully below In the direction of arrow A, this isfollowed by a heat treatment device f, through which the backing fabrice coated with the paste is conveyed. Downstream thereof there isprovided a further roll pair g, which bring the backing fabric eprovided with the overlay to a desired thickness, before the fabric, inthe form of a coated backing fabric, is coiled onto a take-up reel h.

The calender illustrated in FIG. 2, in a first embodiment of the method,is designated overall as 2 and comprises an upper roll 2 a and a lower,preferably roughened roll 2 b forming a nip therewith, wherein the lowerroll 2 b is associated with a third roll 2 c in such a way that, byvarying the position of the third roll 2 c, for example displacing it inthe direction of arrow B or vice versa or by displacing it in thedirection of arrow C or vice versa, the looping distance of the backingfabric 1 round the roll 2 b may be adjusted as desired.

In order to apply the pasty overlay material to the backing fabric 1 inthe embodiment illustrated in FIG. 2, the backing fabric 1 is guidedthrough the nip of the calender 2, which is formed by the rolls 2 a and2 b, wherein in particular the amount of overlay material applied may bevaried by varying the amount of pasty overlay material supplied, by thelinear pressure and by the viscosity of the pasty material.

The second embodiment of the method shown in FIG. 3 does not differfundamentally from the above-described embodiment with regard to thecalender 2. Here too, the calender 2 comprises an upper roll 2 a and alower roll 2 b cooperating and forming the nip therewith, wherein thesurface of the roll 2 b has preferably been roughened. Below the lowerroll 2 b there is likewise provided a third roll 2 c, wherein this roll2 c is preferably mounted so as to be movable in direction B or indirection C or contrary to these two directions, such that the loopingdistance of the backing fabric around the roll 2 b may be varied asdesired by appropriate movement and adjusted to the respectiverequirements.

Unlike in the above-described embodiment, the rolls 2 a to 2 c are notarranged vertically above one another but rather are inclined at anangle ax of approximately 15° relative to vertical, whereby it may beensured in a particularly simple manner that the backing fabric 1 is fedsubstantially horizontally to the nip formed between the rolls 2 a and 2b. In this embodiment according to FIG. 3 too, the looping distance ofthe backing fabric e around the roll 2 b after coating may be changed bydisplacement of the third roll 2 c in the direction of arrow B or Cand/or contrary thereto.

Like the above-described embodiment, the third embodiment of the methodillustrated in FIG. 4 likewise comprises a calender 2 comprising anupper roll 2 a, a lower roll 2 b and a third roll 2 c arrangedtherebelow. In this embodiment, the rolls 2 a and 2 b are inclinedrelative to vertical by an angle α of approximately 15°, as in FIG. 3.

In addition, the third embodiment shown in FIG. 4 comprises a fourthroll 2 d arranged downstream of the calender 2 in the backing fabricconveying direction, wherein this roll 2 d is likewise mounted so as tobe movable preferably in direction B or in direction C or contrary tothese two directions, such that the looping distance of the backingfabric around the roll 2 b may be changed as desired by appropriatemovement and adjusted to the respective requirements. The embodimentillustrated in FIG. 4 differs from the embodiment discussed above andillustrated in FIG. 2 in that, in the embodiment according to FIG. 4,the loop passes firstly round the third roll 2 c and only then round thelower roll 2 b and in that a fourth roll 2 d is provided, such that thelooping distance of the backing fabric 1 around the lower roll 2 b maybe adjusted by changing the position of one or both of the rolls 2 c and2 d, i.e. by displacement in direction C and/or in direction B.

The fourth embodiment of the method illustrated in FIG. 5 likewiseprovides a calender 2, but this calender comprises only an upper roll 2a and a preferably roughened lower roll 2 b cooperating therewith. Thesetwo rolls 2 a and 2 b form the nip necessary for coating.

The diameter of the upper roll 2 a amounts at most to 70% of thedianieter of the lower roll 2 b and the nip is positioned relative tothe winding axis of the supply roller a and to the entry slit of theheat treatment device f in such a way that immediately before, duringand after coating the backing fabric 1 lies on the appropriatelyroughened surface of the lower roll 2 b, in order to achieve the desiredone-sided coating of the backing fabric mainly on the top face, as shownin FIG. 1.

The rolls 2 a and 2 b described above in relation to the first to thirdexemplary embodiments and illustrated in FIGS. 2 to 4 together with theroll 2 a illustrated in FIG. 5 preferably exhibit diameters of between90 mm and 300 mm, wherein the respective lower roll 2 b always has aroughened surface.

1. A method of producing bearing materials, in which a web of a metallicbacking fabric is provided continuously with an overlay covering thebacking fabric on one side and mainly containing polytetrafluoroethylene(PTFE), characterized in that the backing fabric is coated on its topface with a paste of the overlay material and in that the backing fabricis guided during and immediately after coating with its bottom face hiall-over contact with a roll.
 2. A method according to claim 1,characterized in that, for coating purposes, the web of hacking fabricis guided through the nip of a calender comprising an upper roll and alower roll, in such a way that the bottom face of the backing fabriclies on the surface of the lower roll.
 3. A method according to claim 2,characterized in that the web of backing fabric is guided through thenip of a calender whose upper roll has a smaller diameter than the lowerroll and/or whose lower roll is roughened.
 4. A method according toclaim 3, characterized in that the web of backing fabric is guidedthrough the nip of a calender whose upper roll has a diameter <70% ofthe diameter of the lower roll.
 5. A method according to one of claims 1to 4, characterized in that a roll is selected as lower roll whosesurface facing the bottom face of the backing fabric is provided withuniformly distributed particles and/or unevennesses of the order ofbetween 5 μm and 50 μm, preferably between 10 μm and 30 μm.
 6. A methodaccording to one of the preceding claims, characterized in that thesurface of the lower roll is provided with a wrapping of paper, plasticsand/or textiles.
 7. A method according to claim 6, characterized in thata film of biaxially oriented polyester or biaxially orientedpolycarbonate is selected as the wrapping.
 8. A method according toclaim 5, characterized in that the surface of the lower roll issandblasted or engraved to form the particles.
 9. A method according toone of the preceding claims, characterized in that the backing fabric isfed to the calender in such a way that it loops in part round the lowerroll, wherein the looping distance amounts to at least 1%, preferablymore than 3%, of the circLIumferenice of the loweer roll.
 10. A methodaccording to one of the preceding claims, characterized in that thebacking fabric is guided horizontally during coating.
 11. A methodaccording to claim 9 or claim 10, characterized in that a third roll isassociated with the calender, which is positioned downstream of the nipwhen viewed in the backing fabric conveying direction, and in that thebacking fabric is guided with its top face in contact with the thirdroll.
 12. A method according to claim 8 or claim 9, characterized inthat the upper roll of the calender is inclined relative to vertical byan angle of 50 to 25°.
 13. A method according to one of the precedingclaims, characterized in that the consistency of the paste is adjustedsolely by the addition of a wetting agent.
 14. A method according toclaim 13, characterized in that a non-ionic wetting agent, preferably awetting agent based on an alkyl polyglycol ether, is selected as wettingagent.
 15. A method according to one of the preceding claims,characterized in that the overlay material paste contains, in additionto polytetrafluoroethylene (PTFE), also at least one hightemperature-resistant polymer.
 16. A method according to claim 15,characterized in that the at least one high temperature-resistantpolymer is selected from the group comprising fully aromatic polyesters,fully aromatic polyamides, polyetherether ketones and/or polyphenylenesulfones.
 17. A method according to claim 15 or claim 16, characterizedin that a paste is selected which comprises, in addition topolytetrafluoroethylene (PTFE), between 20 and 60 vol. % of the hightemperattire-resistant polymer.
 18. A method according to one of claims15 to 17, characterized in that up to 50 vol. % of thepolytetrafluoroetliylene (PTFE) is replaced bypoly(tetrafluoroethylene-co-perfluorovinyl methyl ether) (PFA),poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP),poly(hexafluoroisobutylene-covinylidene fluoride) (CM-1),poly(ethylene-alt-tetrafluoroethylene) (ETFE) and/or polyvinylidenefluoride (PVDF).
 19. A method according to one of the preceding claims,characterized in that an overlay material paste is selected in which upto 50 vol. % of the high temperature-resistant polymer is replaced bymolybdenum sulfide, tungsten sulfide, boron nitride, graphite, lead,lead oxide, iron oxides, calcium fluoride, glass and/or ceramic powderand/or glass and/or carbon fibers.
 20. A method according to one of thepreceding claims, characterized in that the coated backing fabric issubjected to a heat treatment after coating thereof.
 21. A bearingmaterial produced according to one of claims 1 to 20, having a backingfabric, wherein the backing fabric has on its top face an overlaypredominantly of polytetrafluoroethylene (PTFE) and as far as possiblehas no overlay oil its other surface.
 22. Use of the bearing materialproduced according to one of claims 1 to 20 as a sliding clement inflanged hushes, especially for vehicle door hinges.